The present invention relates to a lens group shifting mechanism for zoom binoculars and, more specifically, an encased shifting mechanism for shifting the movable lens group of zoom binoculars having a minimum portion to be water-tightly sealed.
Conventional zoom binoculars are known, including ocular lens elements, objective lens elements, prism members and a shiftable zoom lens group, all within an outer cylinder. Various mechanisms are known for longitudinally moving the shiftable lens group along the longitudinal axis of the cylinder. However, the known shifting mechanism is generally movable longitudinally from the outside of the outer cylinder. This is a disadvantage when the zoom binoculars are desired to be water-tightly sealed. The various gaps and surfaces which result are very difficult, if not impossible, to water-tightly seal.